Cathode-ray tube timing pulse generator for radar systems and the like



J. L. RUSSELL ET AL CATI-IODE-RAY TUBE TIMING PULSE GENERATOR FOR RADAR SYSTEMS AND THE LIKE 2 Sheets-Sheet 1 May 19, 1953 Filed Dc. 16, 1945 TIMING KEYER IT TIMEDVELAYIK HJEQ: OSCILLATOR CIRCUIT '0 F 1 I I I 8 AMPLIFIER l GATING I1z- =1 E TIMING 5-0? KEYER OSCILLATOR -vv-ll- AMPLIFIER 3 26 I 21 ZIWW'MM 25 JAMES L.RUSSELL T ELVIN E.HERMAN y 19, 1953 J. L. RUSSELL ET AL 2,639,425

CATHODE-RAY TUBE TIMING PULSE GENERATOR FOR RADAR SYSTEMS AND THE LIKE Filed Dec. 16, 1943 2 Sheets-Sheet 2 TRANSMITTER DUPLEXER R ECElVER SW EEP K EY E R GEN ERATC.

l? TIMEDELAY TIMING CIRCUIT OSCILLATOR IO 1 (2 ['8 H AMPLIFIER GATING CIRCUIT JAMES L.RUSSELL ELVIN E.HERMAN Patented May 19, 1 953 UNITED STATES CATHODE-RAY TUBE TIMING PULSE GEN- ERATOR FOR RADAR SYSTEMS AND THE LIKE James L. Russell and Elvin E, Herman, Washington, D. C.

Application December 16, 1943, Serial No. 514,486

(Granted under Title 565, )U. S. Code (1952),

r 12 Claims.

sec.

This invention relates to the generation of timing impulses and is particularly directed to the determination of the time interval separating two events.

Accordingly, it is an object of the invention to provide a timing impulse generator for generating a series of impulses inaugurated in definite time relation with an event.

It is a further object of the invention to provide a series of timing impulses of high accuracy.

Another object of the invention is to provide means for generating impulses spaced at a desired interval selected by adjustable control means.

A specific object of the invention is to pro vide means for calibrating the time base of an echo ranging system.

The invention provides for generation of timing impulses by scanning a charge pattern sustaining surface. The target surface is recurrently swept with an electron beam to establish a voltage distribution along the sweep path. The charge sustaining surface is provided with a conductive backing plate to enable a signal output to be taken off.

The charge sustaining surface may, for instance, be of the inconoscope mosaic type, although photoemission is of no advantage. A convenient arrangement employs a conventional cathode ray tube provided with a backing sheath consisting of a metallic foil or conductive coating. Such coating may be obtained by applying a carbon suspension such as Aquadag over the tube envelope at the end carrying the fluorescent screen. The phosphor itself is not necessary and the inner face of the tube need not be coated, although it is convenient to view the sweep locus on the inner face to the end wall to ascertain that the tube is operating properly.

The scanning beam establishes a potential under the spot which is in part a function of the beam current. Normally the current level is fixed, and therefore a uniform potential obtains along the sweep locus.

The beam, which is continuously swept, is modulated or deflected from the sweep locus by an impulse at the start of the timing period. This action establishes a departure at the scanning point from the distribution pattern potential of the locus, and on the subsequent sweep over the point generates an impulse in the tar get output circuit as the voltage at the scanning point is shifted toward that of the normal potential along the sweep. The target output circuit may be capacitatively coupled to the 2 targetas isthe signal plate backing an iconoscope mosaic, or it may be fed from the attendant current variations in the collector or second anode circuit.

In order that the period between imposition of the voltage departure on the target and the output impulse may accord with the sweep period, manifestly the sweep path must not retrace any common point during a sweep cycle, as a voltage discontinuity established on such a point will be retraced to supply an output impulse before the full cycle is completed. Suitable sweeps will therefore trace around a portion of the target area, and will be referred to as defining a closed sweep locus. For simplicity in the sweep generating circuits a circular pattern supplied by a sine wave oscillator and phase splitting circuit is desirable.

Under the system so far described the operation will supply a single impulse following the magurating impulse by a single oscillator period where the normal scanning beam wholly restores the voltage departure to the pattern value at the point. However, operating conditions in the tube may be obtained to shift the potential incrementally on each succeeding sweep until the pattern potential is reached, and thereby generate a plurality of output signals each followmg another by the sweep period.

The latter operation produces output impulses of limited amplitude and requires more stringent storage characteristic of the target. The invention contemplates alternatively the generation of a series of timing impulses through reestablishing a voltage departure on the sweep locus under control of the target output signal. This is accomplished by feeding the output signal through a time delay circuit and back to the beam control means. In this embodiment the interval between impulses is the sweep period plus the delay time. By suitably controlling transmission through the feedback circuit reestablishing the voltage departure in response to the inaugurating impulse, the system may be caused to terminate operation after a selected number of pulses, and is ready for a subsequent timing operation.

The principles of the present invention are manifestly adaptable to the continuous generasignal whose time relations are to ed. I V be deter The system of the present invention will be further described in connection with reference to the exemplary specific embodiments shown in the drawings, in which Fig. 1 is; the circuit diagram ofga tirning im- 5 pulse generator,

Fig. 2 is the circuit diagram of another em: bodiment of the invention, and

Fig. 3 is the circuit diagrarn vof anzecho ra-n efiinding system incorporating. the present; vention.

As shown in Fig. 1, the system includesstorage tube I provided with the conventir'm-a-lgun el'ef ments 2, 3, 4, and 5, deflection electrodes fijand fluorescent screen I. The HIJQQ QIj-V-ElQDfiiifijQX ternally coated with a conductive sheath 8 The gun elements are energized across divider [9. The electron beam is constantlm sweptover a circular, or approximately circular, pattern by timing oscillator 9 and phase splitting network Qs lla or v may. h a o v n i na t pe: 02 sine, wa enera tunable'by. en knobi -lp ov de min impul es ats l ted f'er l i, or a crystal controlled high fre'duencyfpreci sion oscillator.

n er e; wnstant. eunpotentiais; in, fillfi $y c tern shown, the electron beam.estamisse aj m; form potential] on, target, surface 7i, alien w p locus. The iniatine' at terminals f5; and. operates, a/ crate a standard inip ilse'... 'Ke'. pl nimpul e s i tT 'ex le d 'dwav' 1' r it may r sp nd ,to' an. m other type. 'Infcase anfinitiating to e al en rated 5 t .ks er mani stlyfi t er ill, etnsce corporated in theci'rcuit. Keyer l'fi the Kipp, relay unbalanced multivi The keyer impulse, wave of Shfilit, duration, 1 circuit L7 for-inst I taneo'usly the keyin ing: circuit, [8,. r qr f mplifi r. 10. di-nsh he impulse-mo, e. tQraee. ube bx. maintainin its oper i n. dur n he; imi ed 1 51. a toimperiod.- l n L A g, Ig is opfirativfistoisupply;atcon-i W91 1' iaae. uration. iinuteab itne. time nstant. of its, circuit; components. In, theisysm tam- 11088 11; 1 5. iye irn'lgiulfiezis.generatedi which.

p 7 rater-,typewhich.issnonmally:ineactive, but; may; be keyed. into. another conditionto. holdthe amplifier; 201m operation. The ci rcuitis further; charactenizedijmthatzfor a period after reyerting ,ta the original. conditiom'it is; insensitive to keying; impulse$gandl.thereaiiterisv again sensitive .to; an, inauguratin imnu'lseifrom. keyer [6. v v

-Amplifier 2Q, sup ggliea the impulseztox rid 3 of he ath derartubet toembduiatethe beam current and establish a depa gturew fmm. the normal voltage, on the, target; the; sweep point; Preferably the polarity o f thewcontmli grid signal. will be shel as to; decrease the beamcurrent. v

The operation of -the; system: requires. that the. voltage departime; thereb GQQ ZGQd on: the: sweep locusbe tal enoif;E on th negtzcycl'eiandzthemre-i. establish on the locus again. The output signal is generated across resistor 25. There is present in the output circuit, however, in addition to the signals generated on the wiping sweeps which remove the voltage departure signals which occur at the, moment of reco ding when the beam is modulated. This latter series of signals per forms no useful function, and being of opposite sign from the desired series of timing impulses, may be rejected, by suitable rectifier means.

It, isialsot preferred that the feedback circuit re-record the timing impulse series of signals throughv negative modulation of the beam current the same manner as the inaugurating signal was recorded.

Where operating conditions in the storage tube are, such that electron storage occurs, the timing impulse on the succeeding cycle is of the same polarity; as therecorded grid signal. Under these conditions, therefore, the feedback system will be non-inverting, and the unilateral network reject; the nwan e s o m ulses- In E time: t n ne impul e on. h wiring; w e e nd; components I? and 29 supply these; eta-negative; impulses to: grid-e. The positi ignal; accom- Denying the. recordin is blocked: his! ec ifier: 225-.

- Where. excess. s condary emiss on. xistsdurh ins recording, the timing;impulsa s area i;01inch site. polarityfrem the recording; impulses; ap-

plied-tether grid, andconsequently the: unilateral impedance. will" be arranged to pass theseaimpulses; and the feedback; circuit. including com-e ponents i i: and 20: williinvertpthei samezat. grid-, 3;.

The process is repetitive until the end ofi,

gating period. which. renders:v amplifier: 25E inoperative-w to. disable the feedback circuit. and". termie nate generation of the timing impulses,at.terminals. 2i; Thefinab timing impulse generated on the. sweep. succeeding the: gatingl period does-- not key the gating circuit lqlgdue tolthe insensitivity thereof immediately following the gating.

period.

A- simplified: circuit is shown in. Fig. 2 wherein thedmpulse-signal supplied to'the grid- 3 of oathperiod through incremental restoration ofjth e pat-ternpotential;

Application of the timing-- impulse generator in a radio echosystemis shownpin- Fig: 3, The" radar is'a conventional circuitiinpluding an impulse transmitter. 3.0. tripped bykeyer; 3i" and" feeding a directionalantenna 32 through d uplexing-network 3J3: Receiver 34* feeds theecho,

signals to viewing tubetewhich issuppliediwith a timing sweep fromgenerator 33 synchronized] with the transmitter repetition cycle.v

Timing; impulses: are appliedito the. viewing, tube from the output of cathode raytube, I, The

timing system is directly fedby. the transmitter.

keyer-cr and functionsto establish a: voltage departure'ontarget-surface' 'i oftube I which re suits, onthe succeeding trace thereover; in" a timing output signal indicated as a deflection perpendicular to the time base onview-ingtube; 35 Such impulsesarerepeated until amplifier 28' is: disabledby gating: circuit [8, and furnish:- calibration points on theviewing tube.- Mani-- ct fier 2e conducts: he: e a? festly the gating period will be shorter than the interval between the radar transmitter pulses. When such system is employed only for verifying the radar range indicator, the application of the timing impulses may be terminated by switch 38.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

We claim:

1. Means for time delaying a momentary input signal comprising a cathode ray tube including a charge pattern sustaining target and a single electron beam generating means, means for periodically tracing the'electron beam generated 'by said single electron beam generating means over a closed locus on said target to establish a voltage distribution along said locus, means modulating said electron beam responsive to the input signal to establish a potential departure from said voltage distribution on said locus on receipt of said signal, and a target output circuit operative to furnish an output signal on the next subsequent trace of said beam over said departure.

2. Means for time delaying a momentary input signal, comprising a cathode ray tube including a charge pattern sustaining target and 'a single electron beam generating means, oscillator means operative to sweep the electron beam generated by said single electron beam generating means over a closed locus on said target to establish a voltage distribution along said locus, means modulating said electron beam responsive to the input signal to establish a potential departure from said distribution on said locus onreceipt of said signal, and a target output circuit operative to furnish an output signal on the next subsequent trace of said beam over said departure.

3. Means for generating recurrent signals at spaced intervals including a charge pattern sustaining target, means for sweeping said target with an electron beam recurrently over a closed locus to establish a voltage distribution along said locus, means for controlling said beam operative to establish a potential departure from said distribution on said locus, target output circuit means operative to supply an output signal on the next succeeding sweep over said potential departure and means operative in dependency on the output signal to establish another potential departure on the sweep locus.

4. Means for generating recurrent signals at spaced intervals including a charge pattern sustaining target, .means for sweeping said target with an electron beam recurrently over a closed locus to establish a voltage distribution along said locus, means for controlling said beam operative to establish a potential departure from said distribution on said locus, target output circuit means operative to supply an output signal on the next succeeding sweep over said potential departure, and means including a time delay circuit fed by the output circuit operative to establish another potential departure on the sweep locus.

5. Means for generating a series of output signals at equally spaced intervals after an input signal including a charge pattern sustaining target, means for sweeping said target with an electron beam recurrently over a closed locus to establish a voltag distribution along said locus, means responsive to the input signal operative to establish a potential departure from said distribution on said locus on receipt of said signal,

target output circuit means operative to supply an output signal on the next succeeding sweep over said voltage variation, and means operative in dependency on the output signal to establish another potential departure on the sweep locus.

6. Means for generating a limited series of output signals at equally spaced intervals after an input signal including a charge pattern sustaining target, means for sweeping said target with an electron beam recurrently over a closed locus to establish a voltage distribution along said locus, means responsive to the input signal operative to establish a potential departure from said distribution on said locus on receipt of said signal, target output circuit means operative to supply an output signal on the next succeeding sweep over said voltage variation, means operative in dependency on the output signal to establish another potential departure on the sweep locus and means operative after a plurality of signal generation cycles to terminate operation of said last mentioned means.

l 7. Means for repeating a signal including a charge pattern sustaining target, means for recurrently sweeping said target along a locus to establish a voltage distribution thereon, means for establishing the signal as a potential departure from said distribution along said locus, a target output circuit operative to supply said signal as an output signal on the succeeding sweep over said part of the locus, and means including time delay transmission circuit means fed by the output circuit operative to re-establish the signal as a potential departure from said distribution on said locus.

8. In a radar system, an impulse transmitter, and echo receiver, cathode ray tube indicator means including a beam controlling electrode fed by the receiver, means for supplying a timing signal to the indicator including a charge pattern sustaining target, means for recurrently sweeping an electron beam along a closed locus on said target to establish a voltage distribution along said locus, beam control means for establishing a potential departure from said distribution on said locus in definite time relation to the period of transmitter operation, a target output circuit operative to supply a signal on the succeeding sweep over said potential departure, and means coupling an output signal from said target output circuit to the beam controlling electrode of said indicator to establish a timing marker on said indicator.

9. A timing impulse generator including a charg pattern sustaining target, means for recurrently sweeping an electron beam over a closed locus on said target to efiect a voltage distribution pattern along said path, beam control means for effecting a departure from said voltage distribution, a target output circuit, input circuit means for the beam control means including a time delay circuit feeding an amplifier, amplifier control means operative to terminate operation of the amplifier after a timing period, means for simultaneously feeding an input impulse to the amplifier control means and to the time delay circuit to establish a potential departure from the voltage distribution, and means for feeding the output signal generated in the target output circuit on the next succeeding sweep over the potential departure to the time delay circuit to reestablish the signal at another point on the locus, whereby target output circuit pulses are repeated at fixed intervals until termination of the amplifier operation by the amplifier control means.

age-eaten currently sweeping a-nelectron beam over acloset-i? locus.- on said target to effect a' voltage distribution pattern along said path; beam control meansfor--eifecting a departure from said voltage dis-- tribution, a target output circuit, input circuit means'for the beamcentrol means including a time delay circuit feeding-an-amplifier; amplifier control means operativeto terminate operation of the amplifier after-a timing period'; a-iteyer*cir--- cuit' operative to supply an impulse signal simul taneously to the-amplifier control means andto' the-timedelay circuit to establisha potential de'- parture from the voltage distribution, and meansfor feeding the output" signal generated" in the target outputIcircu-it on the" next succeeding sweep over the potential" departure to the timedelay cit-- cui't toreestablish the signal at another point on the locus, whereby target output circuit pulses are'repeat'ed at fixed intervals until termination of the amplifier operation by the amplifier control means.

11. Means for time delaying a momentary input signal comprising a cathode ray tube inc'luding'a charge pattern sustaining targetandtributionalong saidlocus, means modulating said electron beam responsive to the input signal to decrease the beam current to effect a decrease in potential at a-point on-sa-id locus, and a target output circuit operative to furnish an output signal onzthe next subsequent-trace-o1 saidbeam oversaid' point.

lzrMeans" for time delaying a momentaryinputisi'gnai, comprising a cathode-ray tube eluding a: cnarge pattern sustainingtarget and asingle electron beam generating'-means; oscillator meanaa operative to sweep=t-he electron beamgen-- enacted by said single electron beamgenerating means over a closed locus on said target to est'ab--- lish: a voftagedisttibution along said' locus, means modulating said eIe'ctron beam responsive to the input: signal to" establish a potential departurefxzorm sai'd distti'bution on: said locuson' receipt of said signal, a target output? cii' cuit' operative" to furnish an output signal on the nextsubsequent. trace of: beamlover said departure. and means for vanying; the oscillator-z frequency-v L. RUSSELL.

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